What’s the Link Between Cholesterol and Health?
For decades, experts have focused on reducing blood cholesterol levels to lower the risk of heart disease. That's because so-called "bad" LDL-cholesterol is often implicated in the formation of fatty plaques on artery walls. These plaques, which can resemble angry pimples of the sort most of us remember from our adolescent years, are the most visible sign of atherosclerosis. And atherosclerosis is the underlying cause of most heart disease—still our number one killer.
But in recent years experts have discovered that atherosclerosis is more nuanced than that. Simply lowering cholesterol levels is not always enough. For one thing, cholesterol is not all bad. In fact, it's essential. The body needs a constant supply of cholesterol. It's used as a building block to make numerous important hormones and other substances. Our need for cholesterol is so great that we're very good at creating our own supply. This is one of the reasons that advice to lower your dietary intake of cholesterol—from foods like seafood or eggs, for instance—is probably misguided. Only about one-quarter of your blood cholesterol levels at any given time come from the diet. The rest is basically genetic: some bodies are more efficient at making cholesterol than others. But for most of us, about 75% of our blood cholesterol has nothing to do with diet.
There's also the issue of peroxidation. Oxidized LDL-cholesterol is the true culprit in plaque formation. And that's very much linked to diet. A diet high in antioxidants discourages the formation of oxidized cholesterol. Guess which types of diets are rich in antioxidants? Those featuring plenty of whole fruits, grains, vegetables, nuts, and seeds.
There's also the issue of cholesterol fractions. Total cholesterol is comprised of both LDL-cholesterol and "good" HDL-cholesterol. High levels of HDL cholesterol are considered good for the heart. Again, diet seems to have little influence on this beneficial lipid. Exercise has an impact on HDL, as does genetics. Most people who exercise routinely have higher levels of HDL than more sedentary people.
However, there may be another reason to keep cholesterol levels in check. Emerging research suggests that LDL-cholesterol plays a role in cellular mobility. And that could have implications for the ability of cancer cells to spread throughout the body, invade distant tissues, and metastasize. Here, too, HDL cholesterol appears to play a beneficial role, putting the brakes on cell migration.